Systemic AL Amyloidosis with Colonic Submucosal Hematoma.

An 80-year-old man hospitalized with acute chronic heart failure had received anticoagulant therapy for atrial flutter and passed bloody stools. Warfarin was used, and the International Normalized Ratio (INR) was controlled at 1.91. Urgent colonoscopy revealed multiple colonic submucosal hematomas (Picture 1). Colonoscopy repeated one week after discontinuing anticoagulant therapy showed smaller and flatter submucosal hematomas and the development of shallow ulcers (yellow arrows) (Picture 2). A histopathological examination of biopsy specimens showed eosinophilic material positive for Congo red staining deposited mainly in the submucosal layer (Picture 3). Immunohistochemistry was positive for lambda light chain (Picture 4). The findings for serum M protein and IgA lambda type were positive, consistent with a diagnosis of systemic AL amyloidosis. The patient's heart failure was thought to be caused by left ventricular diastolic dysfunction due to amyloid deposition. Systemic AL amyloidosis with colonic submucosal hematoma is rare (1). AL amyloid within the vascular walls increases the vessel fragility and risk of collapse, resulting in hematoma formation (2). In this case, anticoagulant therapy worsened the hematomas.

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